Oil tanning



Patented Jan. 19, 1932 PATENT OFFICE AILENBOGEES, OF BROOKLYN, NEW YORK OIL TANNING No Drawing.

This invention relates to oil tanning; and itcomprises a method of treating hides and fur skins wherein the skin is milled and,

otherwise treated with a soapy composition of pasty nature containing water and alkalicontaining saponified products derived from oils, said composition containing ammonia and formaldehyde and said oils being advantageously marine animal oils; all as more fully hereinafter set forth and as claimed.

Oil tanning, or the samian process of treating hides and skins, is a laborious and time consuming operation. Tanning requires about 10 days. Skins are placed in stocks and the oil added and the skins milled, usually for about four hours. They are then piled down and again milled and so on until the oil is well absorbed when the skins are placed in a warm room to dry out the water and complete the tanning,'being thereafter pressed to remove the excess of oil, washed in a sodium carbonate solution, dried, staked and buffed.

In Patent No. 1,595,872, August 10, 1926, granted to Rogers & Mathur, there is described an improvement in this oil tanning process, simplifying the operation, abbreviatin the time and producing better results.

In 's patented process in lieu of using oil SO-itself saponified oils are employed, the saponification being usually designedly incomplete so that some unchanged oil exists in the product used in tanning. While other oils may be used the patent recommends marine animal oils of the type of cod oil,

' shark liver oil and seal oil, saponified in a special way. In this described method the oils are heated with a strong caustic soda solution of about 20 Baum to about 170 F. Somewhat less soda is employed than is required to saponify all'the oil used. The

asty mixture of water, soap and unchanged oil is directly used in tanning. The patent advances the theory that the unsaturated groups present in the oils contribute to the tanning in some way.

The present invention is an improvement on the process of this patent. I have found that the time of'tanning can .be still further abbreviated and some other advantages se- Application filed March 16, 1929. Serial No. 347,744.

cured, if the stated composition contains some hexamethylene tetramine; or, which is the same thing, ammonia and formaldehyde. In this event not only is the tanning quicker but the tanned leather is easier to wash and withstands a comparatively high temperature. Skins so tanned may be washed with water at as high a temperature as 170 F. without any damage; a fact which makes the present invention particularly advantageous 00 in the production of furs. In practice I may add ammonia and formaldehyde as such to the material after saponification or I may mix the two separately and add the mixture to the saponified product. Ammonia and formaldehyde on admixture react to produce hexamethylene tetramin; and in lieu of adding ammonia and formaldehyde separately, this reaction product may be used as an addition to the saponii ied mass.

In operating under the present invention I ordinarily employ less soda than is indicated in the example of the recited patent. I find it advantageous to use about one-third of the amount of caustic soda required for complete saponification.

In a specific embodiment of the present invention 60 pounds of a marine animal oil, such as cod oil or seal oil, is heated to 150 F. and is emulsified and saponified by a solution of 3 pounds of caustic soda in 15 pounds of water. After emulsification and saponification the mixture is cooled to about 120 F. and 17 pounds of water and 3 pounds of commercial aqua ammonia added. After admixture, 2 pounds of commercial formalde' hyde are added. This produces a tanning composition under the present invention.

While I regard the marine animal oils best for my purposes, vegetable oils such as rapeon seed oil, linseed oil or olive oil may be used.

Material made under the present invention is a smooth, pasty composition of about the consistency of thick cream. In using this composition the skins or hides are milled with it in stocks or. mills for about two hours, using about 30 pounds of the paste thinned with 30 pounds of water for pounds of the average stock. After milling for two hours 20 pounds of the paste is-introduoed and milling resumed, usually for about one hour. The skins are then hung over night or until dry, in a moderately warm room and then dampened and milled again for two hours. The skins are then hung up in a warm loft and allowed to dry slowly, the temperature of the drying room being, advantageously, between 110 and 120 F. A closed room gives the best results. or the like, are washed in warm water, say of 100 F. The water may contain a small amount of soda ash. After washing, the skins are again dried, milled to soften them and finally buffed. If the process is being applied to furs the skins are cleaned in sawdust in place of being washed.

The foregoing directions are, of course, merely given as examplificatory. The amount of compound required of course varies with the nature of the skin. As a rule, however, I use about 50 per cent of compound on the pickled weight of the hides or skins. The described method may be combined with the usual methods of oil tanning. For example in a modified form of my invention, the soapy compound is used for a preliminary treatment and the hides or skins are then treated with straight oil or a mixture of compound and oil. In so doing the weakening effect of straight oil is obviated and more stretch is secured.

What I claim is zp 1. A composition suitable for oil tanning comprising the residue of oils incompletely saponified, ammonia and formaldehyde.

2. A composition suitable for oil tg comprising the residue of marine animal oils incompletely saponified by caustic alkali, ammonia and formaldehyde.

3. A composition suitable for oil tanning comprising ammonia, formaldehyde and the residue of incompletely saponified marine animal oils selected from a class consisting of cod oil, shark liver oil and seal oil.

4. In the samian process of tanning hides and skins the step which comprises treatin said hides and sln'ns with the product 0 claim 1.

5. In the samian and skins the step said hides and claim 2.

6. In the samian process of tanning hides and skins the ste which com rises treating said hides and 'ns with t e product of claim 3.

7. In the samian process of tanning hides and skins the step which comprises treating said hides and skins with the product of claim 1 to partially tan the same and completing the tanning by submitting the said hides and skins to a further oil tanning.

.8. In the samian process of and skins the step Said hides and skins with the product of claim process of tanning hides which comprises treating skins with the product of tanning hides After drying the skins, if chamois' which comprises treating 2 to partially tan the same and completing the tanning by submitting the said hides an skins to a further oil tanning.

9. In the samian process of tanning hides and skins the step which comprises treating said hides and skins with the product of claim 3 to partially tan the same and completing the tanning by submitting the said hides and skins to a further oil tanning.

10. In the oil tanning of hides and skins, the process which comprises milling the said hides and skins for a short time with a paste of the composition of claim 1, drying the said hides and skins, again dampening and milling and thereafter slowly drying.

n testimony whereof, I have hereunto aiiixed my signature.

" ALLEN ROGERS.

Ill 

